Roller mill



FIG. 1 is a perspective view of a roller mill, showing my new design from the top, front and right side;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front elevational view thereof, the rear view being a mirror image; and,

FIG. 5 is a right side view thereof, the left side view being a mirror image.

The broken lines depict portions of the roller mill that form no part of the claim. 

CLAIM The ornamental design for a roller mill, as shown and described. 